/* -*-ePiX-*- */
#include "epix.h"
#include "tolman.h"
using namespace ePiX;

double rad(0.1);
void particle(const P& loc, double sgn)
{
  P utip(loc - P(3*sgn*rad,0)), vtip(loc - P(0,sgn*0.75));
  bold();
  circle(loc, rad);
  arrow(loc - P(3*sgn, 0), utip);
  arrow(loc - P(0, 2*sgn*rad), vtip);

  if (sgn < 0)
    {
      label(vtip, P(4,2*sgn), "$-v$", r);
      label(loc - P(1.5*sgn,0), P(0,-2), "$-u$", b);
    }
  else
    {
      label(vtip, P(4,2*sgn), "$+v$", r);
      label(loc - P(1.5*sgn,0), P(0, 2), "$+u$", t);
    }
}

int main()
{
  picture(P(-3,-1), P(3,1), "3 x 1in");

  begin();
  arrow_init();

  particle(P(-0.75,  0.5), 1);
  particle(P( 0.75, -0.5), -1);

  font_face("sc");
  label(P(0.5*(xmin() + xmax()),ymin()), "Fig.~11.");
  tikz_format();
  end();
}